The present invention relates to a platform chip or high temperature-stable sensor, in which electrodes arranged on a substrate are in contact with a sensitive layer. The invention also relates to an intermediate product, production methods, and applications, particularly to methods for combustion control and for exhaust-gas recirculation.
From German published patent application DE 35 04 498 A1, a high-temperature gas sensor is known for determining gas components in automobile exhaust gases, in which thin-film semiconductor sensors and a heating arrangement are arranged on a substrate. The heating arrangement has a meander shape and the semiconductor sensors engage each other like combs.
European Patent EP 0 738 385 B1 describes a lambda probe having sufficient mechanical and thermal stability relative to the hot and pulsing exhaust gas from internal-combustion engines. For this purpose, a contact track made of platinum is applied on Al2O3 via a bonding agent.
Material fluxes are determined with heated sensors by the energy consumption of the sensor. High-temperature sensors contain platinum-coated chips and are used, for example, at temperatures up to about 450° C. for CO measurement in exhaust gases. At higher temperatures, the chips wear out and therefore are not suitable for long-term use in the range above 600° C., especially above 700° C.
In particular, the resistance or the conductivity of the electrodes changes, whereby the measurements become imprecise and unusable.